Anatomy of the larynx

1. Anatomy
of the LARYNX

2. Shape & Site
• A 2-inch-long, tube shaped organ.
• open into the laryngeal part of the pharynx
above and is continuous with the trachea
below
• It projects forwards in the median region of
the neck extending from the root of tongue
to the trachea ( from the middle of c3
vertebra to the lower border of c6 vertebra)

3. Function
• The larynx is the portion of the respiratory tract
containing the vocal cords
• The larynx functions in:
1. Deglutition (swallowing) protecting the trachea
against food aspiration
2. respiration (breathing)
3. Phonation (voice production) commonly called
the voice box

4. Relations
1. Anteriorly Skin, Fascia,
Infrahyoid m,
Pyramidal lobe
(if present)
2. On each side: Lat. Lobe of thyroid,
Carotid sheath.
3. Posteriorly: Pharynx

5. Structure of the larynx
The larynx is formed by a number of cartilages which are
connected tighter by ligaments & membranes and lined
by mucous memb.

6. 1. Epiglottis
• It’s a leaf like lamella of elastic
cartilage
• It projects upwards behind the
tongue & the hyoid bone
• Its upper end is wide & free
• Its lower end is narrow & fixed
to the inner aspect of the
thyroid prominence

7. 2. Thyroid cartilage
• the largest of the nine cartilages that make up the
laryngeal skeleton.
• composed of two halves, which meet in the middle at
a peak called the laryngeal prominence, also called
the Adam's apple.
• In the midline above the prominence is the superior
thyroid notch. A counterpart notch at the bottom of
the cartilage is called the inferior thyroid notch.
• The post. Border of each lamina has 2 horns:
A- Sup. Horn: attached to the greater horn of hyoid
bone by the lat. Thyroid lig.
b- Inf. Horn: articulates with the cricoid cartilage at
the crico-thyroid joint.

8. 3.Cricoid cartilage
Below thyroid cartilage
• Ring shaped having a broad lamina
post. & narrow arch infront.
• The upper border of the lamina
articulates with the arytenoid
carilages.
• The post.lat. Aspect of the arch
articulates with the inf-horn of the
thyroid cartilage.
• Inferior to it are the rings of cartilage
around the trachea (which are not
continuous - rather they are C-shaped
with a gap posteriorly)

9. 4. Arytenoid cartilages
• Each one is pyramidal in shape having:
1. Apex: articulates with corniculate cartilage.
2. Base: articulates with cricoid cartilage.
3. Vocal process: directed forwards & gives attachment to the vocal lig. (cord).
• Each one articulates with the upper border
of the lamina of cricoid cartilage.
4. Muscular process: directed posterolat.
& gives insertion to the muscles which
move the arytenoid cartilage.

10. 5. Corniculate cartilages
• Each one is small cartilage nodule
lying on the apex of the arytenoid
cartilage.
6. Cuniform Cartilages
• Each one is a small cartilage nodule
lying infront of the corniculate
cartilage in the oryepiglottic fold.

11. Membranes of the larynx
1. Thyroidhyoid membrane
2. The quadrangular membrane
3. Cricothyroid membrane

12. Membranes of the larynx
1. Thyroidhyoid membrane
• Attached above to the deep surface
of hyoid bone near its lower border.
• Attached below to the upper
margin of the thyroid cartilage.
• Pierced by internal laryngeal n. &
sup. Laryngeal a.

13. Membranes of the larynx
2. The quadrangular membrane
• It is the upper part of the fibro-
elastic membrane which lines
the larynx.
• Extends between the arytenoid
cartilage & the epiglottis.
• Its lower border is thickened to
form the vestibular lig. (false
cord)

14. Membranes of the larynx
3. Cricothyroid membrane
• It’s the lower part of the fibroelastic memb.
Lining the larynx.
• The ant. median part called the median
cricothyroid lig.
• the lat. Part of it (on each side) is triangular &
called the cricovocal membrane.
• Its upper border is called the vocal lig. (true
vocal cord) & its attached ant. To the inner
aspect of thyroid prominence & post. To the
vocal process of arytenoid cartilage.

15. Cavity of the larynx
Its divided into 3 compartments by
2 pairs of folds :
1. Upper folds Called “ Vestibular
folds” False vocal cords.
2. Lower folds called “ vocal folds “
true vocal cords.

16. Cavity of the larynx
• Compartments of the larynx:
1. Vestibule (upper compartment)
2. Ventricle or sinus of the larynx
(middle compartment)
3. Infraglottic (lower compartment)

17. Cavity of the larynx
• Rima vestibuli : is the space
between the 2 vestibular
folds.
• Rima glottidis : is the space
between the 2 vocal folds.

18. Muscles of the larynx
Some authors divided the larynx into:
1. Extrinsic Muscles (the longitudinal muscles of the pharynx &
infrahyoid muscles)
2. Intrinsic Muscles (true laryngeal muscles) both attachments on the
laryngeal cartilages.

19. Muscles of the larynx
• Acording to their action they are divided into 5 groups:
1. Muscles which stretch the vocal cords.
2. Muscles which relax the vocal cords.
3. Muscles which abduct the vocal cords.
4. Muscles which adduct the vocal cords.
5. Muscles which adjust the size of the laryngeal entrance.

20. Muscles of the larynx!
1. Muscles which stretch the
vocal cords.
• The 2 cricothyroid muscles:
Act by lowering the thyroid cartilage
forwards so the distance between the
vocal process of arytenoid & the
laryngeal prominence is increased & the
vocal cords become stretched.

21. Muscles of the larynx
2. Muscles which relax the vocal
cords.
• The 2 thyroarytenoid muscles:
they relax the cords by pulling the arytenoid
cartilages forwards towards the laryngeal
prominence.

22. Muscles of the larynx
3. Muscles which abduct the
vocal cords.
• The 2 post. Cricoarytenoids:
They draw the muscular processes of the
artenoid cartilages backwards so that the
vocal prcesses become directed laterally.

23. Muscles of the larynx
4. Muscles which adduct the vocal
cords.
• Transverse arytenoid muscle:
It approximates the 2 arytenoid cartilages to each
other
• 2 lat. Cricoarytenoid muscles:
they draw the muscular process “forwards”, this
makes the vocal processes move medially

24. Muscles of the larynx
5. Muscles which adjust the size of
the laryngeal entrance
• 2 oblique arytenoids muscles:
they encircle the laryngeal orifice acting like a
phincter.
• Aryepiglottic Muscles:
( not powerful to overcome the elasticity of the
epiglottis so they cant close the laryngeal
entrance)

26. Arterial supply of the larynx
• Arterial supply:
1. Sup. Laryngeal a. (branch of sup.
Thyroid a.)
2. Inf. Laryngeal a. (branch of inf.
Thyroid a.)

27. Venous drainage of the larynx
•Venous drainage:
1. Veins of the upper part join the sup.
Thyroid v. which ends in the I.J.V
2. Veins of the lower part join the inf.
Thyroid v. whuch ends in the
innominate v.

28. Lymphatic drainage of the larynx
1. Lymphatics of the vocal cords &
upper part drain into the upper
deep cervical L.Ns.
2. Lymphatics of the lower part drain
into the lower deep cervical L.Ns &
prelaryngeal L.Ns.

29. Nerve supply of the larynx
1. Motor supply of the laryngeal muscles
2. Sensory supply of the mucous membrane

30. Nerve supply of the larynx
1. Motor supply of the laryngeal
muscles:
• All laryngeal muscles are supplied by
the recurrent laryngeal nerves except
cricothyroid m.
• Cricothyroid m. is supplied by the
external laryngeal n.

31. Nerve supply of the larynx
•Sensory supply of the mucous
membrane
1. Above the vocal cords is supplied by
the int. laryngeal n.
2. Below the vocal cords is supplied by
recurrent laryngeal n.